One major topic under study in our laboratory is the role of direct substrates for protein kinase C (PKC) in mediating the many cellular effects resulting from activation of this family of kinases by hormones and other agonists. We have been studying a small family of PKC substrates consisting of MARCKS and its smaller homologue, the MARCKS-like protein or MLP. Ongoing projects include structure-function studies of the protein and its mutant derivatives in two major systems, development of the mouse central nervous system, and early embryogenesis in Xenopus laevis. These studies have involved creating gene knockouts for MARCKS and MLP in the mouse, and using "knockout" oligonucleotides and protein overexpression to perturb early Xenopus development. In addition, transgenic complementation of the knockout mice with mutant proteins is continuing in order to analyze structure function relationships in development. Similar studies are being performed in a cell transfection system, which seeks to examine the effect of the wild-type and mutant proteins on cellular adhesiona and migration on various matrices. Finally, we are currently investigating the possibility that mutations in the MARCKS and MLP genes are involved in human neural tube defects, particularly at the level of increasing a genetic predisposition to environmental causes of these defects.